Slab cross flow cvd reactor

ABSTRACT

A method and system for performing chemical vapor deposition are disclosed. A chemical vapor deposition reactor can have a generally rectangular chamber that is configured for cross flow and/or zone flow control of reactant gases therethrough. One reactant gas can be injected into the chamber from one end thereof to create cross flow. Another reactant gas can be injected through the top of the chamber. Inert gas can be injected into the chamber to enhance flow control. By providing cross flow and zone flow control, more uniform deposition can be obtained. Also, parameters such as gas flows are less coupled to one another and can therefore be more easily controlled.

RELATED APPLICATION

This patent application is a continuation-in-part (CIP) patentapplication of co-pending patent application Ser. No. 11/064,984, filedFeb. 23, 2005 and entitled CHEMICAL VAPOR DEPOSITION REACTOR HAVINGMULTIPLE INLETS (docket no. M-15626-2P US), the entire contents of whichare hereby incorporated explicitly by reference.

TECHNICAL FIELD

The present invention relates generally to chemical vapor deposition(CVD). The present invention relates more particularly to a slab crossflow reactor for providing enhanced parameter control and enhanceddeposition uniformity in chemical vapor deposition processes.

BACKGROUND

Reactors for use in chemical vapor deposition (CVD) are well known. Suchreactors are used to deposit material upon a substrate during themanufacturing of light emitting diodes (LEDs).

Although such CVD reactors have proven generally suitable for theirintended purposes, they possess inherent deficiencies which detract fromtheir overall effectiveness and desirability. Examples of these problemsare discussed below.

The proposed solutions to these problems have, to date, been ineffectivein providing a satisfactory remedy. Therefore, it is desirable toprovide an enhanced CVD reactor.

BRIEF SUMMARY

A method and system for performing chemical vapor deposition aredisclosed. For example, according to a particular embodiment a chemicalvapor deposition reactor can comprise a generally rectangular chamber.The generally rectangular chamber can be configured for cross flowand/or zone flow control of reactant gases.

As a further example, according to a particular embodiment a method forperforming chemical vapor deposition can comprise placing at least onewafer into a generally rectangular chamber. A reactant gas, e.g., NH₃can be injected into the chamber so as to define a cross flow throughthe chamber. Another reactant gas, e.g., a group III gas, can beinjected into the chamber from above using zone flow control.

Alternatively, the group III gas can be injected into the chamber so asto define a cross flow through the chamber and the NH₃ can be injectedinto the chamber from above using zone flow control. Further, inert gascan be injected into the chamber so as to define a cross flow though thechamber and/or from above using zone control. Any desired combination ofgroup III, NH₃, and inert gas can be injected into the chamber so as todefine a cross flow though the chamber and/or from above using zonecontrol. Each different gas, e.g., group III, NH₃, and inert gas, can beinjected into the chamber via a separate set of injectors. Optionally,zone control can be provided at the end of the chamber.

As a further example, according to a particular embodiment a lightemitting diode can be formed by placing at least one wafer into agenerally rectangular chamber. A reactant gas can be injected into thechamber so as to define a cross flow through the chamber and anotherreactant gas can be injected into the chamber from above, optionallyusing zone flow control.

By providing cross flow and/or zone flow control, more uniformdeposition can be obtained. Also, parameters such as gas flows are lesscoupled to one another and are therefore more easily determined andcontrolled.

This invention will be more fully understood in conjunction with thefollowing detailed description taken together with the followingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of one half of a contemporary chemical vapordeposition (CVD) reactor chamber;

FIG. 2 is a top view of the CVD reactor chamber of FIG. 1, wherein arotating table thereof is configured to support seven wafers;

FIG. 3 is a top view of the CVD reactor chamber of FIG. 1, wherein therotating table thereof has five rotating satellites, each of which isconfigured to support three wafers;

FIG. 4 is a side view of another contemporary chemical vapor deposition(CVD) reactor, wherein the chamber is defined by a narrow flow channel;

FIG. 5 is a side view of an example of an embodiment of a slab crossflow CVD reactor, wherein NH₃ is injected into the chamber so as todefine a cross flow through the chamber and group III gas is injectedinto the chamber from above using zone flow control;

FIG. 6 is a top view of the slab cross flow CVD reactor of FIG. 5,better showing the group III injector zones thereof;

FIG. 7 is a side view of another example of an embodiment of a slabcross flow CVD reactor, wherein group III gas is injected into thechamber so as to define a cross flow through the chamber and NH₃ isinjected into the chamber from above using zone flow control;

FIG. 8 is a top view of the slab cross flow CVD reactor of FIG. 7,better showing the NH₃ injector zones thereof;

FIG. 9 is a side view of another example of an embodiment of a slabcross flow CVD reactor wherein both NH₃ and group III gas are injectedinto the chamber so as to define a cross flow through the chamber andinert gas is injected into the chamber from above using zone flowcontrol; and

FIG. 10 is a top view of the slab cross flow CVD reactor of FIG. 9,better showing the inert gas injector zones thereof.

Embodiments of the present invention and their advantages are bestunderstood by referring to the detailed description that follows. Itshould be appreciated that like reference numerals are used to identifylike elements illustrated in one or more of the figures.

DETAILED DESCRIPTION

Systems and methods for enhancing the chemical vapor deposition (CVD)process are disclosed herein. More particularly, according to aparticular example, a chemical vapor deposition reactor can comprise agenerally rectangular chamber. The generally rectangular chamber can beconfigured for cross flow of reactant gases. The generally rectangularchamber can also be configured to facilitate an introduction of gasthrough a top thereof.

At least one, typically a plurality, of gas injectors can be formed at atop of the chamber. At least one, typically a plurality, of gasinjectors can be formed at one end of the chamber. At least one,typically a plurality, of gas exhausts can be formed at the other end ofthe chamber.

The gas injectors at the top of the chamber and/or the gas injectors atthe end of the chamber can be divided into a plurality of individuallycontrollable zones. Thus, gas flow can be controlled on a zone basis.That is, gas flow though each of the injectors in a particular zone canbe collectively controlled. For example, according to such collectivecontrol, a single adjustment can affect gas flow through all of theinjectors within a zone, while not substantially affecting gas flowthrough injectors in other zones.

Alternatively, the gas injectors at the top of the chamber and/or thegas injectors at the end of the chamber can be controlled on anindividual basis. That is, gas flow through each of the injectors can beindividually controlled.

Any desired combination of collective and individual control of the gasinjectors can be provided. For example, gas flow through the injectorsat the top of the chamber can be controlled on a zone basis and gas flowthrough the injectors at the end of the chamber can be controlled on anindividual basis. As a further example, one or more of the injectorswithin a zone can be individually controllable. Indeed, one, more thanone, or all of the injectors can be subject to both zone and individualcontrol.

As a further example, all of the injectors at the top of the chamber canbe considered to be in one zone and can thus be collectively controlled.Similarly, all of the injectors at the end of the chamber can beconsidered to be in one zone and can be controlled collectively.

Any desired number of zones can be provided. Thus, zero, one, two,three, four, five, or more zones can be provided for the injectors atthe top of the chamber and/or for the injectors at the end of thechamber. The injectors at the top of the chamber can have either thesame or a different number of zones with respect to the injectors at theend of the chamber.

Each zone can have any desired number of injectors. For example, eachzone can have between two and fifty injectors. As a further example,each zone can have approximately twenty injectors. The number ofinjectors can vary from zone to zone.

Each zone can be of any desired configuration. Each zone does not haveto have the same configuration as other zones. For example, the zonescan be in the form of longitudinal (in the direction of the cross flow)rows, in the form of transverse (perpendicular to the direction of thecross flow) rows, in a checkerboard pattern, or in the form ofconcentric circles.

The zones can be reconfigurable. For example, by providing individualcontrol of flow through the nozzles, the zones can be software orotherwise configurable so as to have any desired shape or combination ofshapes.

Wafers can be supported within the chamber upon a rotatable wafercarrier. The entire wafer carrier can be rotatable and/or individualsatellites of the wafer table can be rotatable.

One problem with contemporary CVD systems is that an undesirably wideprocess parameter space inherently has to be investigated in an attemptto find the optimum conditions for performing the CVD process.Undesirable interactions often occur between process parameters. Thatis, there is substantial cross-talk between process parameters. Thiscross-talk makes the effect of changing a parameter difficult topredictable in contemporary CVD systems because changing one parametercan undesirably effect a corresponding change in one or more otherparameters. The magnitude and direction (increased or decreased flow),as well as where (upon which wafers or which portions of the wafers) theeffect occurs, can be difficult or impossible to predict.

For example, when there is a desire to increase the group V/III ratio,the increase can be accomplished by increasing the NH₃ flow rate whilefixing the group III flow rate. However, the group III flow toward thewafers will be affected in a manner that frequently necessitatesadjustment of the group III flow rate, as well as the group IIIdistribution. Adjustment of the group III flow rate and distribution arenecessary so as to maintain the same deposition or growth uniformity. Assuch, interaction between the two flow rates is undesirable because itcomplicates the process optimization procedure.

Referring now to FIGS. 1-3, one type of contemporary reactor is commonlyreferred to as planetary reactor. This reactor comprises a cylindricalchamber 100 within which chemical vapor deposition is performed. In suchplanetary reactors, a susceptor or wafer carrier 101 rotates atapproximately 10 rpm and the individual wafer pucks or satellites 102rotate at approximately 50 rpm. One or more wafers 103 rest upon eachsatellite 102.

Gases enter the chamber via a central injection nozzle 104 thatseparates group III gases from group V gases prior to their introductioninto the chamber 100. The injection nozzle 104 is above the wafercarrier 101. The gases can be trimethyl-gallium (TMG) and ammonia (NH₃),for example. A typical wafer size is 2 inches. The exhaust 105 is alsoabove the wafer carrier 101. A heater (not shown) can be disposedbeneath the wafer carrier 101.

With particular reference to FIG. 2, the wafer carrier 101 can beconfigured to support seven wafers 103 via seven satellites 102. Eachsatellite 102 supports one wafer 103. Both the wafer carrier 101 andeach individual satellite 102 rotate, as shown by the arrows, in anattempt to provide uniform deposition upon the wafers 103.

With particular reference to FIG. 3, the wafer carrier 101 canalternatively be configured to support fifteen wafers 103 via fivesatellites 102. In this instance, each satellite 102 supports threewafers 103. Both wafer carrier 101 and each individual satellite 102rotate, as shown by the arrows, in an attempt to provide uniformdeposition upon the wafers 103.

However, such planetary reactors suffer from inherent deficiencies thattend to detract from their overall utility and desirability. Thesedeficiencies include the accumulation of heavy deposits on the chamberceiling due to lack of active gas flow. The deficiencies also includeundesirable gas flow changes along the radial flow direction due toincreased cross-section, which is an inherent source of depositionnon-uniformity in such cylindrical reactors.

Further, the degree of uniformity provided by the averaging effectrealized from rotation of the wafer carrier 101 and/or the satellites102 depends upon the ability to define an optimized zero-rotationdeposition profile. The zero-rotation deposition profile can only beroughly controlled by adjusting the TMG and NH3 flow from the centerinjector. Consequently, control of the deposition profile is not asprecise as is desirable.

Referring now to FIG. 4, another type of contemporary reactor has acylindrical chamber 400 that defines a narrow flow channel. In thisreactor, the group III and group V gases both are distributed over theentire lid 401 via a plurality of group III and group V inlet nozzles orinjectors 402. A wafer carrier 403 supports a plurality of wafers 404.

Each group III injector has a group V injector adjacent to it. Theexhaust 402 is below the wafer carrier 403. Gases flow from theinjectors 402, over the wafers 404, and downwardly toward the exhaust402. Neither the wafer carrier 403 nor the individual wafers 404 rotate.

However, such multiple injector reactors suffer from inherentdeficiencies that tend to detract from their overall utility anddesirability. These deficiencies include lack of deposition uniformity.Since neither the wafer carrier 403 nor the wafers 404 rotate,deposition uniformity is solely dependent on group III sourcedistribution. Although the use of multiple injectors in intended tomitigate this problem, poor uniformity still results due to insufficientand erratic flow of the reactant gases, especially at high growthpressure conditions.

Further, cross talk among process parameters inhibits process controland uniformity. For example, modification of the flow of one gas, suchas by increasing gas flow through one or more injectors, can result inaltered flow of another gas, thus necessitating modification of the flowthrough one or more injectors for the other gas.

More particularly, such all vertical injection inherently results inundesirable turbulence of the gases. This turbulence inhibits desireduniformity in the flow of the gases, especially at high growth pressureconditions, thus inherently resulting in reduced uniformity ofdeposition upon the wafers.

Further, thermophoresis causes the formation of particles in the gasphase, which inhibits the group III gases from reaching the substratesurface. This undesirable effect becomes more severe at higher growthpressures. Because of this undesirable effect, growth efficiencydecreases with pressure.

A further inherent disadvantage of this contemporary multi-injectorconfiguration, as well as other contemporary cylindrical CVD reactorchambers, is that the gas velocity changes in the outward radial flowdirection due to the increasing cross-sectional area of the chamber. Toavoid this problem, the gas flow from the ceiling has to be wellcalculated and controlled, so as to distribute the right amount of gasspatially. Attempting to optimize gas distribution inherently limitsdeposition process robustness and/or parameter value window by placingconstrains upon the suitable gas flows.

Particular embodiments of the slab cross flow CVD reactor provideenhanced deposition control that can, at least to some degree,compensate for the loss of uniformity that occurs according tocontemporary practice. Particular embodiments can provide enhanced,e.g., substantially full, coverage of a wafer with more uniform growth.Further, larger diameter wafers can be accommodated without the need toscale up the chamber size, as is necessary when using contemporary CVDreactor chambers.

According to particular embodiments, substantially simpler injector andexhaust construction can be provided. Injector and exhaust constructioncan be simplified by the use of rectangular chamber geometry, instead ofthe cylindrical chamber geometry that is used in contemporary CVDreactor chambers.

According to particular embodiments, substantially more uniform gas flowspeed is provided throughout the CVD reactor chamber. That is, gas flowspeeds across a cross-section of the gas flow (perpendicular to the gasflow direction), as well as along the direction of gas flow, tend to bemore constant due to the constant cross-sectional area of therectangular CVD reactor chamber along the direction of gas flow. Thespeed of the gases moving along the flow direction will typically beincreasing since gas injected from the top adds to the horizontal crossflow. However, such increasing flow can readily be accommodated sincethe increase is linear with respect to the gas added from the top.

Referring now to FIGS. 5 and 6, an example of an embodiment of a slabcross flow CVD reactor is shown. According to this particularembodiment, NH₃ is injected from one side 501 (the right side as shownin FIGS. 5 and 6) of a generally rectangular reaction chamber 500 andflows horizontally therethrough to define cross flow 503.

In the particular embodiment shown in FIGS. 5 and 6, cross flow 503 isalong the long or longitudinal direction of the chamber 500. However, aslab cross flow CVD reactor can alternatively be configured such thatcross flow is along the short or transverse direction of the chamber.

The NH₃ cross flow 503 can be evenly or unevenly distributed. Individualand/or zone control of the NH₃ gas injectors at the end of the chamber500 facilitates distribution of the NH₃ as desired.

One notable advantage of the slab cross flow CVD reactor is that the gasflow speed in the flow direction can be kept constant because thecross-sectional area of the chamber is not changing substantially alongthe gas flow direction. The cross-section area of the chamber is equalto the height of the chamber multiplied by the width of the chamber,which remain substantially unchanged along the entire cross flow gaspath (from the end injectors 501 to the exhausts 502). Again, the speedof the gases moving along the flow direction will typically beincreasing since gas injected from the top adds to the horizontal crossflow. However, such increasing flow can readily be accommodated sincethe increase is linear with respect to the gas added from the top.

This is in contrast to the contemporary cylindrical design discussedabove, in which NH₃ gas flow radially inherently results in slowing gasspeed because the cross-sectional area in the flow direction of thechamber inherently increases as the gas moves radially outward.

A rotating wafer carrier 504 can support a plurality of wafers 506beneath a plurality of group III injection zones 507 a-507 d. The wafers506 can be supported upon satellites that facilitate the rotation of thewafers, such as while the wafer carrier 504 is also rotating. Eachsatellite can support one or more wafers. However, one advantage of theslab cross flow CVD reactor is a mitigated need to use such satellites,thus simplifying construction and reducing costs. Optionally, satelliterotation can be provided so as to achieve even greater uniformity. Ofcourse, adding satellite rotation increases the complexity of thehardware design.

The wafer carrier 504 can be constructed, for example, from graphite.The wafer carrier 504 can have a protective coating, such as a coatingof silicon carbide SiC.

According to particular embodiments, more than one wafer carrier can beprovided within a chamber. A plurality of wafer carriers can be providedin a row along the direction of cross flow and/or perpendicular to thedirection of cross flow.

The temperature of the wafers during processing can be controlled by aheater assembly 508, which can be disposed beneath wafer carrier 504.The elements of heater assembly 508 can be of the resistive type and canbe operated by applying electrical current so as to generate thermalradiation that heats the graphite wafer carrier 504 and therefore thewafers 506 supported thereby. Alternatively, temperature control can beprovided by any other desired means.

A floor 510 generally surrounds wafer carrier 504 so as to define asubstantially flat surface or slab. The wafer carrier 504 can beconfigured such that the upper surfaces of the wafers 506 aresubstantially flush with the floor 510 to further define the slab. Theflat surface of the slab tends to minimize undesirable turbulence andthus promotes more uniform cross flow.

Group III gas can be injected from a perforated ceiling 509 having aplurality of individually controllable zones 507 a-507 d, as discussedabove. Since the deposition profile of the resulting film is determined,at least in part, by the distribution of the group III gas impingementupon the wafer's surface, the use of separate zones facilitates bettercontrol of film uniformity across the wafer carrier 504.

Rotation of the wafer carrier 504 and/or the individual wafers 506through the plurality of group III flows coming from above provides adesirable averaging effect during deposition. Rotation of wafer carrier504 can move wafers 506 through a plurality of zones 507 a-507 d toenhance such averaging.

Referring now to FIGS. 7 and 8, according to another example of anembodiment of a slab cross flow CVD reactor, the group III gas and theNH₃ can be reversed with respect to how there are injected. That is, thegroup III gas can be injected into the chamber so as to define a crossflow through the chamber and the NH₃ can injected into the chamber fromabove using zone flow control. Group III gas can be injected into thechamber from one end (such as side 501) of the chamber.

Reversing the injection of the group III gas and the NH₃ can inhibitparasitic reaction of these with respect to the previously describedembodiment. Better separation of the gases prior to reaching the waferscan be achieved.

Referring now to FIGS. 9 and 10, according to another example of anembodiment of a slab cross flow CVD reactor, both the group III gas andthe NH₃ can be injected into the chamber so as to define a cross flowthrough the chamber and inert gas can injected into the chamber fromabove using zone flow control. Group III gas and NH₃ can be injectedinto the chamber from one end (such as side 501) of the chamber.Separate injectors can be used for the group III gas and the NH₃ so asto inhibit premature mixing and reaction thereof.

The inert gas can comprise N₂ or H₂, for example. Those skilled in theart will appreciate that various other gases and combinations of gasesare likewise suitable.

Deposition uniformity can be controlled by varying the flow rates of thegroup III gas and the NH₃. The wafer carriers or satellites can berotated to further enhance deposition uniformity.

The group III gas injectors and the NH₃ injectors can be isolated fromone another to further inhibit premature mixing and reaction of thesegases. Such isolation can be effected, for example, by a partition 901that extends from the wall of the chamber where the injectors arelocated partially into the chamber. The partition 901 prevents the groupIII gas and the NH₃ from mixing until these gases have traveled closerto the wafers. In this manner, parasitic reactions can be inhibited.

A plurality of such partitions (either horizontal as shown or vertical)can be used to effect such separation of the gases. Such partitions canbe placed elsewhere within the chamber so as to control gas flow (suchas to provide more laminar flow), as desired.

Rather than a mechanical partition, such as partition 901 of FIGS. 9 and10, inert gas partition can be used to maintain separation of the gasesprior to their reaching the wafers. The inert gas can function as apartition. That is, inert gas can be injected between adjacent group IIIgas and NH₃ injectors so as to function as a barrier. For example, acomparatively thin layer of inert gas can be so injected such that theinert gas functions as a barrier between the group III gas and the NH₃proximate the injectors and such that the inert gas dissipates (loses itability to function as a barrier) as the gases approach the wafers.

The injection of inert gas from the ceiling using zone flow control caninhibit thermal convection so as to provide more efficient and uniformmaterial deposition upon the wafers. The injection of inert gas from theceiling can also inhibit the undesirable deposition of materials uponthe ceiling. This reduces downtime for cleaning and thereby increasesthroughput. Inhibiting such deposits upon the ceiling also tends toprovide enhanced consistence between runs.

For each embodiment, the gas or gases injected from the side, i.e., thegases that provide cross flow, can be either evenly distributed ornon-evenly distributed, both horizontally and vertically. The flowdistribution, whether even or non-even, can be controlled by even ornon-even positioning of the nozzles. For example, the nozzles can becloser together near the ends of a horizontal row than in the middle ofthe row, so as to provide increased gas flow proximate the side walls ofthe chamber in a manner that tends to compensate for resistance to flowcaused by the side walls. Similarly, the flow distribution can becontrolled by the flow rates through the injectors.

Embodiments provide enhanced uniformity of growth over the entire areaof a wafer, as opposed to the bands of circles of non-uniform coverageprovided by some contemporary chemical vapor deposition systems.Consequently, larger diameter wafers are more readily accommodatedwithout requiring a scale up of the chamber size. Injector and exhaustconstruction is simplified by the linear, e.g., rectangular, chambergeometry (as opposed to the cylindrical chamber geometer of prior artchambers). The more uniform flow speed provided by the rectangularchamber, which is due at least in part to the substantially constantcross-section thereof, further enhances deposition uniformity.

By enhancing deposition uniformity across the whole wafer carrier 504,particular embodiments facilitate configuration of the carrier toaccommodate various numbers of wafers and wafer sizes. Moreover, largerwafer sizes can more readily be accommodated without the need to scaleup the chamber size.

According to particular embodiments, a wide process parameter space doesnot have to be investigated to find the optimum process conditions.Further, undesirable interaction between process parameters ismitigated. Thus, the effect of changing the value of one parameter in aCVD process tends to be more isolated to only the changed parameter andnot to other parameters. That is, there is mitigated cross-talk betweenparameters such as flow rates. Thus, the effect of changing a parameteris substantially more predictable than in contemporary CVD systems.

The slab cross flow chamber of the present invention can providesubstantially more uniform deposition of materials as compared tocontemporary chemical vapor deposition chambers with reduced trade-offswith other growth attributes such as growth rate, growth pressures, etc.More uniform deposition can result from the combination of cross flow ofNH₃ and the use of zone or individually controllable group III injectorson the top of the chamber. Turbulence is substantially mitigated, thusresulting in enhanced controllability of processing parameter, such asgas flow rates, and also resulting in more uniform deposition,particular under higher growth pressure conditions. More uniformdeposition and enhance parameter control tend to result in improvedyield.

Embodiments described above illustrate, but do not limit, the invention.It should also be understood that numerous modifications and variationsare possible in accordance with the principles of the present invention.Accordingly, the scope of the invention is defined only by the followingclaims.

1. A chemical vapor deposition reactor comprising: a generallyrectangular chamber; wherein the chamber is configured for cross flow ofreactant gas; and wherein the chamber is configured to facilitate anintroduction of gas through a top thereof.
 2. The chemical vapordeposition reactor as recited in claim 1, further comprising: at leastone gas injector at the top of the chamber; at least one gas injector atone end of the chamber; and at least one gas exhaust at another end ofthe chamber.
 3. The chemical vapor deposition reactor as recited inclaim 1, further comprising a plurality of gas injectors at the top ofthe chamber.
 4. The chemical vapor deposition reactor as recited inclaim 1, further comprising a plurality of gas injectors at the top ofthe chamber, the gas injectors at the top of the chamber beingconfigured so as to facilitate the injection of group III gas.
 5. Thechemical vapor deposition reactor as recited in claim 1, furthercomprising a plurality of gas injectors at the top of the chamber, thegas injectors at the top of the chamber being configured so as tofacilitate the injection of NH₃.
 6. The chemical vapor depositionreactor as recited in claim 1, further comprising a plurality of gasinjectors at the top of the chamber, the gas injectors at the top of thechamber being configured so as to facilitate the injection of inert gas.7. The chemical vapor deposition reactor as recited in claim 1, furthercomprising a plurality of gas injectors at one end of the chamber. 8.The chemical vapor deposition reactor as recited in claim 1, furthercomprising a plurality of gas injectors at one end of the chamber, thegas injectors at the end of the chamber being configured so as tofacilitate the injection of group III gas.
 9. The chemical vapordeposition reactor as recited in claim 1, further comprising a pluralityof gas injectors at one end of the chamber, the gas injectors at the endof the chamber being configured so as to facilitate the injection ofNH₃.
 10. The chemical vapor deposition reactor as recited in claim 1,further comprising a plurality of gas injectors at one end of thechamber, a plurality of the gas injectors at the end of the chamberbeing configured so as to facilitate the injection of NH₃ and anotherplurality the gas injectors at the end of the chamber being configuredso as to facilitate the injection of group III gas.
 11. The chemicalvapor deposition reactor as recited in claim 1, further comprising: aplurality of gas injectors at one end of the chamber, a plurality of thegas injectors at the end of the chamber being configured so as tofacilitate the injection of NH₃ and another plurality the gas injectorsat the end of the chamber being configured so as to facilitate theinjection of group III gas; and a partition for mitigating parasiticreaction of the NH₃ and the group III gas.
 12. The chemical vapordeposition reactor as recited in claim 1, further comprising a pluralityof gas injectors at the top of the chamber, wherein the gas injectors atthe top of the chamber are divided into a plurality of individuallycontrollable zones.
 13. The chemical vapor deposition reactor as recitedin claim 1, further comprising a plurality of gas injectors at one endof the chamber, wherein the gas injectors at the end of the chamber aredivided into a plurality of individually controllable zones.
 14. Thechemical vapor deposition reactor as recited in claim 1, furthercomprising a plurality of gas injectors at the top of the chamber,wherein the gas injectors at the top of the chamber are individuallycontrollable.
 15. The chemical vapor deposition reactor as recited inclaim 1, further comprising a plurality of gas injectors at one end ofthe chamber, wherein the gas injectors at the end of the chamber areindividually controllable.
 16. The chemical vapor deposition reactor asrecited in claim 1, further comprising a rotatable wafer carrier. 17.The chemical vapor deposition reactor as recited in claim 1, furthercomprising at least one partition configured so as to enhance flowcontrol of at least one reactant gas.
 18. The chemical vapor depositionreactor as recited in claim 1, further comprising at least one injectorconfigured to inject inert gas so as to enhance flow control of at leastone reactant gas.
 19. A method for performing chemical vapor deposition,the method comprising: placing at least one wafer into a generallyrectangular chamber; injecting reactant gas into the chamber so as todefine cross flow through the chamber; and further comprising injectingdifferent reactant gas or inert gas into the chamber through a topthereof.
 20. The method as recited in claim 19, further comprising:injecting group III gas through the top of the chamber; injecting NH₃ atone end of the chamber; and removing gas at another end of the chamber.21. The method as recited in claim 19, further comprising: injecting NH₃through the top of the chamber; injecting group III gas at one end ofthe chamber; and removing gas at another end of the chamber.
 22. Themethod as recited in claim 19, further comprising: injecting inert gasthrough the top of the chamber; injecting NH₃ and group III gas at oneend of the chamber; and removing gas at another end of the chamber. 23.The method as recited in claim 19, further comprising: injecting inertgas through the top of the chamber; injecting NH₃ and group III gas atone end of the chamber; maintaining separation of the NH₃ and group IIIgas prior to the NH₃ and group III gas reaching a wafer; and removinggas at another end of the chamber.
 24. The method as recited in claim19, further comprising injecting group III gas through a plurality ofgas injectors at the top of the chamber.
 25. The method as recited inclaim 19, further comprising injecting NH₃ through a plurality of gasinjectors at one end of the chamber.
 26. The method as recited in claim19, further comprising controlling flow through a plurality of differentzones of gas injectors at the top of the chamber.
 27. The method asrecited in claim 19, further comprising controlling flow through aplurality of different zones of gas injectors at one end of the chamber.28. The method as recited in claim 19, further comprising individuallycontrolling flow through a plurality of different gas injectors at thetop of the chamber.
 29. The method as recited in claim 19, furthercomprising individually controlling flow through a plurality ofdifferent gas injectors at an end of the chamber.
 30. The method asrecited in claim 19, further comprising rotating a plurality of waferswithin the chamber.
 31. The method as recited in claim 19, furthercomprising using at least one partition to enhance flow control of atleast one reactant gas.
 32. The method as recited in claim 19, furthercomprising using at least one injector configured to inject inert gas soas to enhance flow control of at least one reactant gas.
 33. A chemicalvapor deposition reactor comprising: a generally rectangular chamber;means for defining cross flow of reactant gas through the chamber; andmeans for injecting different reactant gas or inert gas into the chamberthrough a top thereof.
 34. The chemical vapor deposition reactor asrecited in claim 33, further comprising: means for injecting group IIIgas through the top of the chamber; means for injecting NH₃ gas at oneend of the chamber; and means for removing gas at another end of thechamber.
 35. The chemical vapor deposition reactor as recited in claim33, further comprising: means for injecting group III gas and NH₃through an end of the chamber; and means for maintaining separation ofthe group III gas and NH₃ as they flow part of the way through thechamber.
 36. The chemical vapor deposition reactor as recited in claim33, further comprising means for injecting group III gas at the top ofthe chamber.
 37. The chemical vapor deposition reactor as recited inclaim 33, further comprising means for injecting NH₃ at one end of thechamber.
 38. The chemical vapor deposition reactor as recited in claim33, further comprising means for individually controlling flow through aplurality of different zones of gas injectors at the top of the chamber.39. The chemical vapor deposition reactor as recited in claim 33,further comprising means for individually controlling flow through aplurality of different zones of gas injectors at one end of the chamber.40. The chemical vapor deposition reactor as recited in claim 33,further comprising means for individually controlling flow through aplurality of different gas injectors at the top of the chamber.
 41. Thechemical vapor deposition reactor as recited in claim 33, furthercomprising means for individually controlling flow through a pluralityof different gas injectors at an end of the chamber.
 42. The chemicalvapor deposition reactor as recited in claim 33, further comprisingmeans for rotating a plurality of wafers within the chamber.
 43. Thechemical vapor deposition reactor as recited in claim 33, furthercomprising means for maintaining separation of the group III gas and NH₃as they flow part of the way through the chamber.
 44. A light emittingdiode formed by a method for performing chemical vapor deposition, themethod comprising: placing at least one wafer into a generallyrectangular chamber; injecting a reactant gas into the chamber so as todefine cross flow through the chamber; and injecting different reactantgas or inert gas into the chamber through a top thereof.
 45. The lightemitting diode as recited in claim 44, wherein the method furthercomprises: injecting group III gas through the top of the chamber;injecting NH₃ gas at one end of the chamber; and removing gas at anotherend of the chamber.
 46. The light emitting diode as recited in claim 44,wherein the method further comprises: Injecting NH₃ through the top ofthe chamber; injecting group III gas at one end of the chamber; andremoving gas at another end of the chamber.
 47. The light emitting diodeas recited in claim 44, wherein the method further comprises: injectinginert gas through the top of the chamber; injecting NH₃ and group IIIgas at one end of the chamber; and removing gas at another end of thechamber.
 48. The light emitting diode as recited in claim 44, whereinthe method further comprises: injecting inert gas through the top of thechamber; injecting NH₃ and group III gas at one end of the chamber;maintaining separation of the NH₃ and group III gas as the NH₃ and groupIII gas flows through the chamber prior to the NH₃ and group III gasreaching a wafer; and removing gas at another end of the chamber. 49.The light emitting diode as recited in claim 44, wherein the methodfurther comprises injecting group III gas through a plurality of gasinjectors at the top of the chamber.
 50. The light emitting diode asrecited in claim 44, wherein the method further comprises injecting NH₃through a plurality of gas injectors at one end of the chamber.
 51. Thelight emitting diode as recited in claim 44, wherein the method furthercomprises individually controlling flow through a plurality of differentzones of gas injectors at the top of the chamber.
 52. The light emittingdiode as recited in claim 44, wherein the method further comprisesindividually controlling flow through a plurality of different zones ofgas injectors at one end of the chamber.
 53. The light emitting diode asrecited in claim 44, wherein the method further comprises individuallycontrolling flow through a plurality of different gas injectors at thetop of the chamber.
 54. The light emitting diode as recited in claim 44,wherein the method further comprises individually controlling flowthrough a plurality of different gas injectors at an end of the chamber.55. The light emitting diode as recited in claim 44, wherein the methodfurther comprises rotating a plurality of wafers within the chamber. 56.The light emitting diode as recited in claim 44, wherein the methodfurther comprises maintaining separation of the group III gas and NH₃ asthey flow part of the way through the chamber.